As the saving of energy and the comfort of occupants become increasingly important, buildings and dwellings are more often provided with air exchange devices so that the air inside the conditioned space, be replaced constantly or from time to time. For example, construction codes in some regions require that new homes and buildings be provided with such air exchange devices. These devices are connected to the ductwork of the air conditioning system or provided with an independent ductwork. The main purpose of these devices is to replace air while transferring heat between the exhaust air and the incoming fresh air. As a result, energy is saved by pre-cooling or pre-heating the incoming fresh air with the exhaust air instead of having to fully heat or cool it while the exhaust air is drawn outside in pure waste.
Installation of an air exchange device often requires air ducts, controls, space and labor costs in addition to the conventional air conditioning device.